The Internet of Things (IoT) introduces objects or things to Human-to-Human (H2H) based Internet services. It marks a stage of the Internet where physical or virtual objects are interconnected to enable the Internet of Services (IoS). Many of these services are proximity based, such as smart shopping, smart home, smart office, smart health, smart transportation, smart parking, smart grid, and smart city, among other things.
Proximity services may be based on peer-to-peer (P2P) communications in proximity. P2P devices include tablets, smart phones, music players, game consoles, personal digital assistances, laptops/PCs, medical devices, connected cars, smart meters, sensors, gateways, monitors, alarms, set-top boxes, printers, Google glasses, drones, and service robots, among other things. A P2P communication system may be a central system with a controller or core network serving as an infrastructure, or a distributed system without a controller or core network serving as the infrastructure. Proximity services may include human-to-human (H2H) proximity services, machine-to-machine (M2M) proximity services, machine-to-human (M2H) proximity services, human-to-machine (H2M) proximity services, and network of network proximity services.
Proximity-based applications and services represent a trend to offload heavy local internet traffic from a core infrastructure as well as provide the connections to an infrastructure via multi-hopping. Many standards have identified proximity services use cases as part of their standardization working groups, such as 3GPP, oneM2M, IETF, IEEE, and OMA. Service layer, as well as cross-layer techniques, is an area of standardization to enable these services.
Proximity services may use wireless networks that have varying acknowledgement (i.e., ACK) mechanisms for reliable data transmission as specified in IEEE 802.15 and IEEE 802.11 standard series.
“IEEE 802.15.4e, MAC Enhancement for IEEE 802.15.4-2006” ACK information element (IE) is defined for the coordinator to acknowledge multiple data frames transmitted in guaranteed time slot (GTS). Group ACK serves to allocate a new time slot for retransmission. An ACK frame can contain additional contents as IEs. Multi-channel adaptation and switch are defined for a sender and receiver pair to switch their communication channel.
In “IEEE 802.15.4k in PHY/MAC Amendment for Low Energy Critical Infrastructure Networks,” increment ACK (LACK) is defined to assist reliable MAC fragments transmission. Each LACK indicates both successfully transmitted fragments and failed fragments. LACK can be described as a combination of ACK and NACK.
In IETF Constrained Application Protocol (CoAP), there is ACK and retransmission in the CoAP protocol. In essence, a CoAP client first sends a request to a CoAP server. Then the CoAP server needs to send an ACK back to the CoAP client if the request needs to be confirmed. In addition, CoAP server can also piggyback a response together with the ACK. Such ACK and response are CoAP-level functions related to applications, which are completely independent of MAC-layer ACK. No matter whether there is MAC-layer ACK or not, CoAP protocol will work in such ways: separated CoAP ACK and CoAP response or piggybacked CoAP ACK and CoAP response as specified in IETF CoAP.
The conventional acknowledgement (e.g., ACK) mechanisms for reliable data transmission, such as the above, may be further optimized.